Photographic element with emulsion layer containing color former and wetting agent



United States PatentO PHOTOGRAPHIC ELEMENT WITH EMULSION LAYERCONTAINING COLOR FORM R AND "WETTING AGENT Benjamin R.-Harriman,Binghamton, N. Y., assignor to .General Aniline & Film Corporation, NewYork,

Y., a corporation of Delaware No Drawing. Application April 30, 1954,

Serial No. 426,929

Claims. (Cl. 95-69 This invention relates to color photography and moreparticularly to color forming gelatino silver halide emulsions andemulsion layers containing non-ionic wetting agents derived frombranched-chain aliphatic alcohols. .It relates further to photographicelements and multilayer color materials containing such emulsion layers.

Conventional subtractive multilayer materials are composed of separateemulsion layers sensitized to the primary colors of the spectrum,namely, blue, green and red, and contain color formers fast to diffusionwhich, upon development with primary aromatic amino developing agents,yield azomethine, indoaniline or phenazonium (azine) dye images. It iscustomary to separate these emulsion layers by intermediate gelatinlayers which serve as separating layers and if colored by the additionof a dye, act also as filter layers. These separating layers preventcolor falsification which Occurs otherwise as the result of themigration of silver halide grains and color formers of two adjoiningemulsion layers. The top layer of the multilayer element is overcoatedwith a gelatin layer which serves primarily as an antiabrasion layer butmay contain an ultraviolet absorbing substance. Generally, theseintermediate or surface gelatin layers are coated immediately as soon asthe emulsion layer which it is supposed to cover has been coated andchilled and it is not necessary to .dry the emulsion layer before it isovercoated.

It is necessary to add saponin or synthetic surface active agents to theemulsion and clear gelatin layers to permit the even wetting of thesupport or of the layer coated onto the support. The surface activeagents arealso needed in order to avoid the formation of repellencyspots which mayvary in size from those barely visible, to those severalinches in diameter.

Among the most useful color formers available to the photographicindustry are those-which contain a ben-v zimidazole nucleus which isfurther substituted by a long chain alkyl group attached to one of thenitrogen atoms, and a. sulfonioor carboxylic'acid group. However,gelatino silver halide emulsion layers containing this type of colorformer suffer from the'serious shortcoming that they cannot be,overcoated in the chilled state with plain gelatin layers in theconventional manner. For some reason, air bubbles are formed when faceactiveagents such as saponin or the conventional synthetic surfactants.

In order to avoid these unacceptable defects, it has been necessary upto now to dry completely the emulsions containing the benzimidazolesubstituted color former before overcoating them with the warm gelatinsolution of the separating layer. This intermediate dry ing involved aserious loss of time,"tied up the coating machinery and resulted in aserious reduction in output.

It is, therefore, an object of the present invention to provide for theovercoating of photographic emulsions containing a color former with abenzimidazole nucleus with warm gelatin solution without necessitatingthe intermediate drying of the emulsions.

Other objects will be apparent from the following description of theinvention.

I have found that a photographic emulsion containing a color former inwhich the color forming portion of the moleculeris linked directly tothe carbon atom in the 2-position of a benzimidazole nucleus, and inwhich the benzimidazole nucleus is further substituted by a longaliphatic hydrocarbon chain attached to the nitrogen atom in thel-position and by a water solubilizing group such as a sulfonic orcarboxylic acid group which is attached to the benzene ring, can beovercoated immediately after chilling and without intermediate drying byadding to this emulsion, a non-ionic wetting agent which is the reactionproduct of a branched-chain monohydric alcohol with ethylene oxide.

The reaction products of ethylene oxide and branchedchain aliphaticalcohols are prepared in accordance with the procedure given in U. S.Patent 1,970,578 with the exception that branched-chain alcohols areused in place of the normal (straight-chain) alcohols disclosed in'thispatent. In general, the reaction products of this invention are preparedby reacting one molar equivalent of the-.branched-chain monohydricalcohol with from 5 to. 20 molar equivalents of ethylene oxide. Thereaction is carried out at elevated temperatures and under pressure inthe presence of suitable catalysts or in aqueous alkaline or acidsolutions as described in U. S. Patent 1,970,578.- The reaction productsobtained have at room temperature, the consistency of wax, sirup orhoney and are soluble in water and in the lower alcohols such asmethanol, ethanol, n-propanol, isopropanol or mixtures of these alcoholswith water. The reaction products are characterized by the followinggeneral formula: T

wherein R is a branched-chain'alkyl group having from 8 to 18 varbonatoms and n represents an integer from 4 to 19. i

The following alcohols are illustrative of the branchedchain monohydricalcohols which can be reacted with ethylene oxide to yield thesurfactants utilized in a0- cordance with" this invention.2ethylhexanol-1 1,1-dimethyldecanol-l Z-n-butyloctanol-l4-n-butyloctanol-l 2,5 ,8 -trimethylnonanol-5 2,6,8-trimethylnonanol-42-ethyldecanol-1 2-n-propylnonanol-l 2,2-dimethyldecanol-12,6-dimethyldecanol-6 4-methyl-4-propyloctanol-5 Z-methyldodecanol-l3-methyldodecanol-3 Z-methyldodecanol-Z 2-butylnonanol-l 2,5,9-trimethyldecanol-5 3-ethylundecanol-3 3 3-methyldodecanol-32,8-di'methyl-S-ethylnunanol 3,3,5 -triethylheptanol-4 2,3,3,5 ,5,6-hexamethylheptanol-4 2-methyltridecanol-3 '3-n-butyldecano1-12,8-dimethyl-5-propylnonanol-5 Z-n-pentylnona'nol-l7-ethyl2-methylundecanol-4 2,8-dimethyl-5-isobutylnonanol-5 3,7,1l-trim'ethyldodecanol-l 3,3,5 ,5 tetraethylheptanol-42,4-dimethyltridecanol-4 7-me'thylpentadecanol-92,6,7,'l1-tetramethyldodecanol-6 2,8-dirnethyl-5 -isoamylnonanol-S 3,9-diethyl'tridecanol-6 2,6,10-trimethylpentadecanol-2 The amounts ofthe reaction product employed range from 0.005% to 2.0% based on theweight of dry gelatin used in the preparation of the liquid emulsioncontaining the benzimidazole substituted color former. The reactionproducts of the branched-chain monohydric alco 1101 and ethylene oxideare compatible in these emulsions with saponin; the combined use ofthese two surfactants has the added advantage of spreading the emulsioncoating more evenly.

It has already been proposed to use various non-ionic wetting agents inphotographic color emulsions for a variety of purposes including theprevention of static and fog, and improved dispersion of the colorformers in the emulsion. However, the surfactants recommended by theprior art are incapable of accomplishing the immediate overcoating of achilled emulsion containing a benzimidazole substituted color formerwith a warm gelatin solution and necessitate the intermediate drying ofthe emulsion.

The. color formers used contain, in their molecule, a benzimidazolenucleus which is substituted on the nitrogen atom in the 1-position byan alkyl chain of at least 10 carbon atoms and substituted in the5-position by a water solubilizing group, and in which the benzimidazolenucleus is connected through its carbon atom in the 2-position to theresidue of a color forming residue which is reactive with the oxidationproducts of a primary amino developing agent and contains a reactivemethylene or ethenol or phenolic hydroxyl group. These color formers arecharacterized by the following general formula:

wherein R is a radical containing a reactive methylene, ethenol orphenolic hydroxyl group capable of reacting with the oxidation productsof an aromatic amino developing agent to form an azomethine, indoanilineor phenazonium dyestufi, R2 is an alkyl chain containing at least 10carbon atoms, e. g., decyl, undecyl, dodecyl, tetradecyl, pentadecyl,hexadecyl, octadecyl and the like, and R3 is a water solubilizing groupsuch as sul fo, carboxy and the like.

More particularly, color formers containing a benzimidazcle nucleus aspart of the molecule and capable of forming dye images upon developmentwith a dialkylarninoaniline developing agent are illustrated by thefollowing structural formulae:

and

wherein R1 is a hydroxy aromatic radical, such as-substituted orunsubstituted hydroxynaphthyl, hydroxyphenyl and the like, the hydroxygroup being nuclear attached,

and said radical 'being linked to the benzimidazole radical inortho-position to said hydroxygroup, R4 is a phenyl radical, R5 is thegrouping NH-COCH2A in which A is an alkyloyl radical, e. g., acetyl,propionyl, butyryl and the like, an aroyl radical, e. g., benzoyl,

naphthoyl and the like, a cyano or carbethoxy group a and R2 and R3 havethe same values as above. .Suitable examples of color formers embracedby these general formulae are disclosed in U. S. Patents 2,545,687 and2.547,307 in which their method of preparation is also described.

Color formers substituted by a benzimidazole nucleus and capable offorming magenta phenazonium (azine) dye images upon development witheither the triaminobenzene developers described in U. S. Patent2,486,440 or with N,N-dialkylphenylenediamine developers are 'disclosedin L. C. Hensleys copending application Serial No. 293,643, filed June14, 1952, now United States Patent 2,701,766, entitled Developers forand 'Method of Producing Phenazonium Dyestuif Images withp-Dialkylaminoaniline Developing Agents. They are characterized by thefollowing general formula:

, Example I To 1 kilogram of a liquid gelatino silver halide emulsionsensitized to red light and containing about 80 grams of gelatin, 50grams .of silver bromo iodide and 5 grams ofl-oct-adecyl-Z-[2'-.(l'-hydroxynaphthyl)lbenzimidazole-S-sulfonic acidas a .color former which'is characterized bythe following structuralformula:

there was added 1.25 grams of saponin and 'milli grams of the reactionproduct of 1 molar equivalent of 2,6,8-trimethylnonanol-4 and 12 molarequivalents 'of ethylene oxide prepared in analogy to theprocedure-described in Example 19 of U. S. Patent 1,970,578. Thisemulsion was coated upon a cellulose acetate film base, chilled andimmediately overcoated with a warm i'aqueous solution of gelatin havinga temperature .of-.40 iC.,and

containing 20 grams of gelatin and 1 gram of saponin per liter. Thecoating was dried, exposed in a sensitometer and developed to a cyanimage with a color developer containing a p-dialkylaminoaniline as thedeveloping agent After shortstopping, bleaching, fixing and washing, thecolor developed film was dried. It was completely free of air bubbles,whereas a comparison sample which had been prepared in an analogousmanner except that the condensation product of 2,4,6-trimethylnonanol- 4and ethylene oxide had been omitted showed a large number of air.bubbles which were visible to the naked eye andbecame more pronouncedupon projection.

Example 11 To one kilogram of a gelatino silver halide emulsion asdescribed in Example I, there was added as a cyan color former, 6 gramsof 1-octadecyl-2'-[2-(1-hydroxy- 7'-methyl)naphthyl]benzimidazole-S-sulfonic acid having the following structural formula:

o (m on. H018 N/ w Example 111 One gram of saponin, 0.175 gram of thereaction product of 1 molar equivalent of 2,6,8-trimethylnonanol- 4',-l2 molar equivalents of ethylene oxide and live grams of the yellowcolor former'bf 2 -(4'-,benz oylacetaminophenyl)-1-octadecylbenzimidazole-5-sulfonic acid having the followingstructural formula:

were added to a blue sensitive gelatino silver halide emulsion.Thisemulsi-on was'coated onto a cellulose acetate filmbase, chilled andimmediately overcoated with. a wann 2% gelatin 'solution containing LOgram of saponin per 'liter.1 "Tlie-rriaterial was dried, exposed througha'trans'parency, developed'in a black and white developer, Lshortstopped, 'color developed in a developer containi jg,N-'di-'(p-'hydroxyethyl)phenylenediamine as the color developing agent,shortstopped, bleached, fixed, washed,, andjdried.' A positive "yellow:azomethin'e dye image was obtained which was completely free fromairbubbles, whereas 1; comparison sample which had been prepared inaiiidentical manner except that the con; densation'product of2,6,8-trimethylnonanol-4 and ethyl ene 'oxidehad been omitted wasstreaky and majrr'ed'by large air bubbles; v

, Example IV Example HI "was repeated with the exception that the 5grams of2-(4'-benzoylacetaminophenyl)-1=octadecylbenzirnidzizol-S-sulfonic acidwere replaced by' 7 grams 6 of 2[ 3',5'-'dibenzoyl-acetamino) phenyl]-l-octadecylbenzimidazole-5sulfonic acidhaving the following structuralformula:

/ I IH-oO-wHmO-Q i 7 1511-0 O-CHaC 0 Six grams of the magenta colorformer 2-[4-(6-bromo: 8-hydroxy 2-(2'-sulfophenyl) -cinchoninoyl)-aminophenyll-1-octadecyl-5-sulfobenzimidazole having the followingstructural formula:

" V rag" son; were added together with 0.2 gram of the reactionproductuof 2,6,8-trimethylnonanol- 4 and ethyleneoxide...and

0.8 gram of saponin toa green sensitive emulsion which was coated onto;the cellulose acetate film base, chilled and immediately overcoated withan aqueous gelatin solutioncontaining 22 grams of gelatin and 1.2 gramsof saponin per-..liter,and having a temperature of 40 .C. 'I l 1ematerial is dried, exposed with green-light through a blackand white;transparency, developed in a' color developer containing4-(di-B-hydroxyethyl)-aminoaniline as the color developing agent,shortstopped, hardened,

bleached, fixed, washed and dried. The finished magenta positive wasfree from air bubbles, whereas a comparison sample from which. thereaction product of 2,6,8-trimethylnonanol-4 and ethylene oxide had beenomitted was unusable because it contained a great number of large airbubbles. I

. Example VI A cellulose acetatejbutyrate film base was'coated with ared sensitive emulsion containing 5 grams of l-octadecyl-2-[2'-(1-hydroxynaphthyl)] benzimidazole-S-s'ulfonic acid, 1.25'grams of saponin,0.15 gram of the reaction prdduct of ethylene oxide and 2,6,8-nonanol-4asdescribed inExar nple I; The red sensitive emulsion was chilled andimmediately overcoated with a warm 2% gelatin solution which contained.5 gram of saponin per liter.- This'gelatin layer was chilled andovercoated with agreen sensitive silver halide emulsion containing, perkilogramflfgrams of 1=(4-phenoxy-3' sulfophenyl)-3 stearyl-Sepyr'azoleand'.5 gram er saponin. The green sensitive emulsion was chilled aftercoating and overcoated with a 2% clear gelatin containing 0.5 gram ofsaponin per liter. The gelatin layer was chilled and overcoated with ablue sensitive emulsion containing 2 (4 -benzoylacetarninophenyl) loctadecylbenzimidw zole-S-sulfonic acid, 0.175 gram of the reactionproduct of ethylene oxide and 2,6,8-trimethylnonanol-4, and 1L0 gram ofsaponin as described in Example III. This blue sensitive'emulsion waschilled and overcoated with a clear gelatin antiabrasion layer whichcontained 0.5 gram of saponin per liter.

The finished multilayer color film was. dried, exposed through amulticolor transparency and processed by reversal development to aduplicate color transparency. The color developed material wascompletely free of air bubbles. A comparison sample which had beenprepared without the use of the reaction product of ethylene oxide andthe branched-chain alcohol was strealcy, contained a large number of airbubbles and was unsuitable for projection purposes. The formation. ofair bubbles in another comparison sample could be avoided only by dryingthe red sensitive and the blue sensitive emulsion layers. containing thebenzimidazole substituted color formers before overcoating them with thegelatin separation and anti-abrasion gelatin coatings. However, thisintermediate drying had the disadvantage of extending the time neededfor the coating operation and thus reducing the potential output of thecoating equipment.

While the present invention has been described with reference to certainpreferred procedures, materials and uses, it is understood that theinvention is not limited thereto, that numerous variations may be madein the procedures herein described and that equivalent materials may besubstituted. For example, benzimidazole substituted color formers andaromatic amino developing agents other than those specifically mentionedand utilized in the foregoing examples may be used. Accordingly, I donot intend to be limited in the patent granted except as necessitated bythe appended claims.

I claim:

1. A photographic element comprising a light sensitive gelatino silverhalide layer containing a color former fast to diffusion and capable offorming, upon color development with a primary aromatic amino developingagent, a dye image selected from the glass consisting of azornethine,indoani'line and phenazonium dye images, said color former containing-a-benzimidazole nucleus connected through its carbon atoms in the2-position to the residue of the color forming molecule which isreactive with the oxidation product of a primary developing agent andcontains a reactive group selected from the class consisting of areactive methylene, ethenol and phenolic hydroxy group, saidbenzimidazole nucleus being substituted on one of the nitrogen atoms byalong chain ailphatic group and substituted in the benzene portion by awater solubilizing group, said emulsion containing as a surface activeagent, the non-ionic reaction product of a branched-chain monohydricalcohol and ethylene oxide characterized by the following generalformula;

wherein R is a branched chain alkyl group having from 8 to 18 carbonatoms, and n is an integer from 4 to 19.

2. .A photographic element comprising'a support bearing a photographicgelatino silver halide emulsion layer containing a color former fast todifiusion which is reactive with the oxidation products of a primaryamino developing agent to yield, upon exposure and development with aprimary amino developing-agent, a dye image selected from the groupconsisting of azomethine, indoaniline and phenazonium dyes, saidcolor'former containing a benzimidazole radical characterized byzthe following generalformula:

wherein R is the residue of the color forming molecule and contains agroup selected from the class consisting of methylene, ethenol andphenolic hydroxy groups capable of reacting with the oxidation productsof the primary amino developing; agent, R2 is. an aliphatic hydrocarbonradical containing at least 10 carbon atoms, Rs is a water solubilizinggroup and the carbon in the 2- position, is linked to the residue of thecolor formingmolecule whichcontains: a reactive group selected from thegroup consistingvof methylene, ethenol and. phenolic hydroxy. groups,said emulsion. containing a nonionic. surfactantcharacterized by thefollowing general formula:

wherein R is: a branched-chain alkyl group having; from 8 to 18 carbonatoms and n is an integer from 4 to 1'9.

3. A photographic element comprising a support bearing a photographicsilver halide emulsion layer containing, in addition to a benzimidazolesubstituted color former selected'from the class corresponding to thefollowing formulae:

s C-R:

C-Rt-(Ru). r-

and

({JONH -Ih-(l Ra X Rs wherein R1 is a hydroxy, aromatic radical, thehydroxy group being nuclear attached, and said radical being linked tothe benzimidazole nucleus in ortho position to" said hydroxy group,Rz'is. an alkyl chain of at least 10 carbon atoms, R3 is a Watersolubilizing group, R4 is a phenyl radical, R5 is the grouping-NH-COCH2A in which A is selected from the group consisting of alkyloyl,aroyl, cyano and carbethoxy groups, R6 is selected from the classconsisting of hydrogen, carboxyalkyl, allyl and lower alkyl groups, andR7 is selected from the class consisting of lower alkyl, allyl, aryl andheterocyclic groups; a non-ionic surfactant characterized by thefollowing general formula:

wherein R is a branched-chain alkyl group having from 8 to. 18 carbonatomsv and n is an integer from 4 to 19.

4. A multilayer photographic color film comprising -a support bearingsuperimposed red, green and blue sensitive gelatino silver halideemulsions containingcolor formerscapable of yielding, upon developmentwith a primaryamino developing agent, a dye image selected from thegroup consisting of 'azomethine, indoaniline and phenazonium dye images,theemulsion layers being in contact with gelatin layers free from silverhalide and at least one of the photographic gelatin silver halideemulsion layers containing a color former having a benzimidazole nucleuswhich'is connected through its carbon atom in the 2-position to theresidue of the color forming molecule which is reactive with theoxidation prodnets of the primary amino developingagent and. containinga reactive group selected from the class consisting of reactivemethylene, ethenol and phenolic. hydroxy groups, said benzimidazolenucleus being substituted on one of the nitrogen atoms by an alkylradical containing at least carbon atoms, and in the benzene portion bya water-solubilizing group, said emulsion containing as a surfactant,the non-ionic reaction product of a branchedchain monohydric alcohol andethylene oxide characterized by the following general formula:

wherein R is a branched-chain alkyl group having from 8 to 18 carbonatoms and n is an integer from 4 to 19.

5. A multilayer photographic color film having a support bearing in thefollowing order, a red sensitive gelatino silver halide emulsion layercontaining a color former, a separating gelatin layer, a green sensitivegelatino silver halide emulsion layer containing a color former, aseparating gelatin layer, a blue sensitive emulsion layer and a gelatinsurface coat, said color formers being fast to diffusion and capable offorming, upon development with a primary amino developing agent, a dyeimage selected from the group consisting of a20- methine, indoanilineand phenazonium dyestuffs complementary in color to the sensitivity ofthe layer in which the color former is incorporated, at least one of thesilver halide emulsion layers containing as the color former, a compoundselected from the class corresponding to the following formulae:

wherein R1 is a hydroxy aromatic radical, the hydroxy group beingnuclear attached, and said radical being linked to the benzimidazolenucleus in ortho position to said hydroxy group, R2 is an alkyl chain ofat least 10 carbon atoms, R3 is a water solubilizing group, R4 is aphenyl radical, R5 is the grouping NHCOCH2A in which A is selected fromthe group consisting of alkyloyl, aroyl, cyano, and carbethoxy groups,R6 is selected from the class consisting of hydrogen, carboxyalkyl,allyl and lower alkyl groups and R7 is selected from the classconsisting of lower alkyl, allyl, aryl and heterocyclic groups; saidemulsion containing a benzimidazole substituted color former containingas a surfactant, the reaction product of said branched-chain monohydricalcohol and ethylene oxide characterized by the following generalformula:

wherein R is a branched-chain alkyl group of from 8 to 18 carbons and nis an integer from 4 to 19.

6. A photographic element according to claim 1 where in said branchedchain alcohol is 2,6,8-trimethylnonan- 01-4.

7. A photographic element according to claim 2 wherein said surfactantis characterized by the following formula:

wherein R is a 2,6,8-trimethylnonanol-4 group.

8. A photographic element according to claim 3 wherein said surfactantis characterized by the following formula:

wherein R is a 2,6,8-trimethylnonanol-4 group.

9. A multilayer photographic color film according to claim 4 whereinsaid branched chain alcohol is 2,6,8- trimethylnonanol-4.

10. A multilayer photographic color film according to claim 5 whereinsaid branched chain alcohol is 2,6,8-trimethylnonanol-4.

References Cited in the file of this patent UNITED STATES PATENTS2,214,205 Potter et al Sept. 10, 1940 2,240,469 Swan et al. Apr. 29,1941 2,393,027 Duerr et al. Jan. 15, 1946 2,545,687 Craig Mar. 20, 19512,547,307 Craig Apr. 3, 1951 2,719,087 Knox et al. Sept. 27, 1955

1. A PHOTOGRAPIC ELEMENT COMPRISING A LIGHT SENSITIVE GELATINO SILVERHALIDE LAYER CONTAINING A COLOR FORMER FAST TO DIFFUSION AND CAPABLE OFFORMING, UPON COLOR DEVELOPMENT WITH A PRIMARY AROMATIC AMINO DEVELOPINGAGENT, A DYE IMAGE SELECTED FROM THE GLASS CONSISTING OF AZOMETHINE,INDOANILINE AND PHENAZONIUM DYE IMAGES, SAID COLOR FORMER CONTAINING ABENZIMIDAZOLE NUCLEUS CONNECTED THROUGH ITS CARBON ATOMS IN THE2-POSITION TO THE RESIDUE OF THE COLOR FORMING MOLECULE WHICH ISREACTIVE WITH THE OXIDATION PRODUCT OF A PRIMARY DEVELOPING AGENT ANDCONTAINS A REACTIVE GROUP SELECTED FROM THE CLASS CONSISTING OF AREACTIVE METHYLENE, ETHENOL AND PHENOLIC HYDROXY GROUP, SAIDBENZIMIDAZOLE NUCLEUS BEING SUBSTITUTED ON ONE OF THE NITROGEN ATOMS BYA LONG CHAIN ALIPHATIC GROUP AND SUBSTITUTED IN THE BENZENE PORTION BY AWATER SOLUBILIZING GROUP, SAID EMULSION CONTAINING AS A SURFACE ACTIVEAGENT, THE NON-IONIC REACTION PRODUCT OF A BRANCHED-CHAIN MONOHYDRICALCOHOL AND ETHYLENE OXIDE CHARACTERIZED BY THE FOLLOWING GENERALFORMULA: